[Trellat]

Of course, but ‘worth’ does not encompass only monetary worth!

[WalterBright]

If nobody wants to pay for X, then X is worthless.

[onraglanroad]

I wouldn't pay anything for any of your family. Or for you.

I'm not sure that's a good measure of worth. Unless you think others would? What's the market value for your family?

[WalterBright]

What you're willing to pay for X is what X is worth to you. It doesn't have to match what anyone else is willing to pay.

It's the basis of the Law of Supply and Demand.